SheikhSafi-ad-din Is''haq Ardabili (of Ardabil) (1252–1334) (Persian: شیخ صفی‌الدین اردبیلی‎), was the Kurdish eponym of the Safavid dynasty, founder of the Safaviyya order, and the spiritual heir and son in law of the great Sufi Murshid (Grand Master) Sheikh Zahed Gilani, of Lahijan in Gilan province in northern Iran. Most of what we know about him comes from the Safvat as-safa, a hagiography written by one of his followers.

Sheikh Safi al-Din''s has composed poems in the Iranian dialect of old Tati. He was a seventh-generation descendant of Firuz Shah Zarrin Kolah, a local Iranian dignitary.

Sheikh Safi al-Din inherited Sheikh Zahed Gilani''s Sufi order, the "Zahediyeh", which he later transformed into his own, the "Safaviyya". Sheikh Zahed Gilani also gave his daughter Bibi Fatemeh in wedlock to his favorite disciple. Sheikh Safi al-Din, in turn, gave a daughter from a previous marriage in wedlock to Shaikh Zahed Gilani''s second-born son. Over the following 170 years, the Safaviyya Order gained political and military power, finally culminating in the foundation of the Safavid dynasty.

Only a very few verses of Sheikh Safi al-Din''s poetry, called Dobaytis (double verses), have survived. Written in old Tati and Persian, they have linguistic importance today.

According to Minorsky, Sheykh Safi al-Din''s ancestor Firuz-shah was a rich man, lived in Gilan and then Kurdish kings gave him Ardabil and its dependencies. Minorsky refers to Sheykh Safi al-Din''s claims tracing back his origins to Hazrath Ali ibn Abu Talib, but expresses uncertainty about this.

The male lineage of the Safavid family given by the oldest manuscript of the Safwat as-Safa is:"(Shaykh) Safi al-Din Abul-Fatah Ishaaq the son of Al-Shaykh Amin al-din Jebrail the son of al-Saaleh Qutb al-Din Abu Bakr the son of Salaah al-Din Rashid the son of Muhammad al-Hafiz al-Kalaam Allah the son of Javaad the son of Pirooz al-Kurdi al-Sanjani (Piruz Shah Zarin Kolah the Kurd of Sanjan)" similar to the ancestry of Sheykh Safi al-Din''s father in law, Sheikh Zahed Gilani, who also hailed from Sanjan, in Greater Khorassan.